Test handle for endodontic root canal treatment



June 13, W67 E. ZDARSKY 3,324,555

TEST HANDLE FOR ENDODONIIC ROOT CANAL TREATMENT Filed Feb. 25, 1964Fig.1 ma

Claims. ei. 32-57 This invention relates to a device for treating theroot canals of teeth.

It is known that root canal instruments such as reamers, files andsmooth broaches are to be employed by measuring the depth of theirinsertion into the root canal. Thus the handle may be provided with ameasuring scale. I have found that a fixation of an adjustableinstrument in the handle is difficult. By turning the screw forfixation, the instrument blade is often displaced again; furtheron sucha fixation does not allow to determine whether the blade is sufiicientlyfixed.

It is, therefore, a principal object of this invention to provide a testhandle which ensures exact adjustment of the blade in the handle. Afurther object of the invention is to ensure the adjusted blade toremain at the determined point in order to make a later displacementimpossible. Still a further object of the invention is to provide a verysimple and handy test handle shape.

To solve this problem the invention provides a test handle on which theblade is longitudinally slidable only within the handle whereby a guidehook of the instrument is transverse-d in a winding path which isturnable in the handle.

In a preferred embodiment of the invention the windin-g path is formedby a screw drive which is turnably located in the cylindrical spacewithin the handle. For turning this screw drive, a turn button isprovided on the exposed end of the handle.

For the fixation of the depth of penetration of the blade only a turningof the turn button with its screw drive is necessary, whereby theinstrument corresponds to the direction of turns and is fixed at anypoint, as the guideway of the screw drive is constructed forself-locking.

The accompanying drawing shows embodiments of test handles according tothe invention.

There are shown:

FIG. 1, a longitudinal cross section of a first model,

FIG. 2, a top view on FIG. 1,

FIG. 3, a longitudinal cross section through a second model,

FIG. 4, a top view on FIG. 3.

On the test handle according to FIGS. 1 and 2 a cylindrical handle 1 onits outside is serrated at 2 in order to achieve a good grip. Inside acylindrical space 3 is provided in which an instrument such as a blade4, is inseited with its shaft 5. The cylindrical handle has a slot 7which is fully open only on the one side of the handle which is oppositeto the instrument blade tip. The width of the slot corresponds to thediameter of the instrument shaft 5 which is bent on the free end to forma guide hook 6. The hook is slidable within the slot and the instrumentcan be taken entirely out of the handle on the open side of the slot.The projecting end of the hook is numbered 8. Inside of the cylindricalspace a screw drive It is turnably mounted. The hook 6 of the instrument3,324,555 Patented June 13, 1967 fits in the screw drive and is movedupwardly and downwardly according to the turns of the screw drive. Inorder to achieve a good fixation and guidance of the instrument, thescrew drive 10 is constructed such so as to fit tightly around theinstrument shaft and to engage with its superposed windings the hook 6.In this way it is possible to guide the instrument without a wobblingmovement.

In order to turn the screw drive, its upper end 11 is engaged by aturning button 12 located in a groove 13 of the test handle.

A serrated head 14 of this turning button provides an easy grip. Alsothe turning button is provided with a slot 15 in order not to handicapinsertion and removal of the instruments. Preferably, the screw drivehas a round cross section in order to reduce friction and wear betweenthe screw drive surface and instrument shaft. In order to obtain aself-locking effect between both parts, the pitch of the screw drive isaccordingly low. The movement of an instrument on the handle 1 can beseen or controlled at the end of the hook. Furthermore, a measuringscale can be provided at the outside of the test handle.

It goes without saying that the screw drive could for example also bemade from a square sectional steel. The turning button 12 can beprovided with a hole only instead of the serrated head 14 in which a pinor the like tool is inserted for turning of the screw drive.

In the embodiment according to FIGS. 3 and 4, the handle 20 is providedwith an outer screw tube 21 which is located turnably in grooves 22 ofthe handle 20.

In a centric axial borehole 23 of the handle, the instrument shaft 5 isguided whereby also a slot 25 allows of longitudinal movement of theguiding hook 6 respective to the instrument. In this case, the end 8 ofthis guide hook 6 projects into a screw drive 26 which is located on theinside of the screw tube 22.

In case the screw tube 21 is turned against the handle 20 which may havea serrated ring, then the instrument moves up and down with its shaft 5Within the slot 25. This slot 25 as well as the screw tube 21 are openon the upper side to allow exchanging of instruments. A measuring scalecan be provided on the surface of the instrument shaft itself.

In order to avoid, by turning the test handle, for example, during theinsertion in the root canal, a dislocation of the screw tube 21 and thehandle part 30 occurs and an adequate safety device can be provided, forexample a key, a bolt or a wedge or a turning tube snapping into apolygon rest located on the handle piece.

I claim:

1. A device for treating tooth-root-canals comprising a handle havingwalls defining a cylindrical cavity and a bottom provided with anaperture, coiling drive means in said cavity, rotary means secured tothe top of said handle, the upper end of said coiling drive meansexcentrically secured to said rotary means for actuation of said drivemeans, a shaft carrying an instrument mounted for axial displacement insaid cavity, said instrument being a small rod-like tool of a sizeadapted to be inserted in a root canal, the lower end of said shaftprojecting through said aperture and the upper end of said shaft beingbent and riding on said coiling drive means, and a longitudinal slot inthe wall of said handle so as to expose the tip of said shaft toobservation from the outside.

2. The device as claimed in claim 1 wherein said upper References Citedend of said shaft projects outwardly through said slot.

3. The device as claimed in claim 1 comprising a cali- UNITED STATESPATENTS bration along said slot. 291,297 1/1884 120-9 4. The device asclaimed in claim 1 wherein said coil- 5 2,494,412 1/1950 slmkms 120-9ing drive means is a rod of round cross section. 311391066 6/1964 Aversa206-56 5. The device as claimed in claim 1 wherein said rotary means isprovided with a radial slot for insertion of the RICHARD GAUDETinstrument. I. W. HINEY, Assistant Examiner.

1. A DEVICE FOR TREATING TOOTH-ROOT-CANALS COMPRISING A HANDLE HAVINGWALLS DEFINING A CYLINDRICAL CAVITY AND A BOTTOM PROVIDED WITH ANAPERTURE, COILING DRIVE MEANS IN SAID CAVITY, ROTARY MEANS SECURED TOTHE TOP OF SAID HANDLE, THE UPPER END OF SAID COILING DRIVE MEANSEXCENTRICALLY SECURED TO SAID ROTARY MEANS FOR ACTUATION OF SAID DRIVEMEANS, A SHAFT CARRYING AN INSTRUMENT MOUNTED FOR AXIAL DISPLACEMENT INSAID CAVITY, SAID INSTRUMENT BEING A SMALL ROD-LIKE TOOL OF A SIZEADAPTED TO BE INSERTED IN